As wireless connectivity becomes more pervasive and reliable, it is expected that all the digital computing, data storage and media storage devices that are in widespread use today will become part of Ad-hoc wireless communication networks. However, such networks are susceptible to data security breaches in many respects. For example, Ad-hoc networks, where individual users communicate with each other directly without using intermediary network nodes, create new susceptibilities to the users and networks.
To reduce the susceptibility of wireless networks, techniques such as wired equivalent privacy (WEP), Wi-Fi protected access (WPA), extensible authentication protocol (EAP) and GSM-based encryption have been developed. Although these techniques provide some protection, they are still susceptible to various trusts, rights, identity, privacy and security issues. For example, although a particular wireless communication node may have the correct WEP keys to communicate with a wireless user, that user may not know whether the particular node can be trusted.
Additionally, authentication of the user using these keys typically occurs at higher layers of the communication stack. Accordingly, even when these controls are in place, a rogue wireless user or hacker may have some (although limited) access to the communication stack. This access creates vulnerabilities, such as denial of service attacks, among others.
The fact that wireless signals degrade with distance introduces a natural measure of security since intercepting a signal requires one to be sufficiently close to the source to detect it. This is particularly true in small networks, where the transmit power is typically low and communications typically occur at highest rates and in an Ad-hoc fashion. In many situations, physical proximity may be the most difficult attribute for a malicious attacker to attain. In fact communication which can only be detected within a very short proximity of the transmitter may not need to be very well protected.
Accordingly, it would be desirable to implement a security system for wireless networks which can take advantage of the natural security offered by degradation of wireless signals. Furthermore, it would be desirable to ensure that any information transmitted to a user is accessible only at the location of the user, such that a “eavesdropper” located in the general proximity of the user, but not at the user's immediate location, is prevented from receiving complete messages transmitted to the user.